A Bayer AG unit withheld from U.S. regulators findings by company researchers of increased reports of blood clots in users of its Yasmin birth-control pills, the former head of the Food and Drug Administration said. David Kessler, the former FDA commissioner, in a document unsealed yesterday in federal court in Illinois, said Bayer didn’t include an analysis “that demonstrated an increase in the U.S. reporting rate” for venous thromboembolism, or clots, in a 2004 review of Yasmin’s safety provided to the agency.